This photo is part of a photo set of a herd of feral horses in Namibia. The set provides an interesting look at daily wild horse behavior, from sparring to napping. Here a few horses keep watch while others rest. Follow the flickr link to enjoy more pictures of these horses.

This article, though it dates from 1999, has some interesting info about the horses. Though I am unaware of their origins, the feral horses of Namibia have become a tourist attraction, and their population is sometimes stricken by drought, as was the case in 1999, when a controversial effort was made to save them.